[BUGFIX] Avoid undef array key in ContentObjectRenderer

Resolves: #99138
Related: #96116
Releases: main, 11.5
Change-Id: I303c6cb4c0cbf9b278f66a34cd49345c18ea2a1c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76705


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Roman Büchler <info@buechler.pro>
Reviewed-by: Roman Büchler <info@buechler.pro>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>